@StructConverter Annotation and <struct-converter> XML

The @StructConverter is an EclipseLink-specific annotation. You can add it to an org.eclipse.persistence.platform.database.DatabasePlatform using its addStructConverter method to enable custom processing of java.sql.Struct types.

Using Structure Converters to Configure Mappings

In EclipseLink, a DatabasePlatform (see Database Platforms) holds a structure converter. An org.eclipse.persistence.database.platform.converters.StructConverter affects all objects of a particular type read into the Session that has that DatabasePlatform. This prevents you from configuring the StructConverter on a mapping-by-mapping basis. To configure mappings that use the StructConverter, you call their setFieldType(java.sql.Types.STRUCT) method. You must call this method on all mappings that the StructConverter will affect – if you do not call it, errors might occur.

The JPA specification requires all @Basic mappings (see @Basic) that map to a non-primitive or a non-primitive-wrapper type have a serialized converter added to them. This enables certain STRUCT types to map to a field without serialization.

You can use the existing @Convert annotation with its value attribute set to the StructConverter name – in this case, EclipseLink will apply appropriate settings to the mapping. This setting will be required on all mappings that use a type for which a StructConverter has been defined. Failing to configure the mapping with the @Convert will cause an error.